Aircraft wing system

ABSTRACT

An aircraft wing system and method comprising: an aircraft wing; an edge device coupled to a leading edge or trailing edge of the aircraft wing; a drive shaft rotatable about its axis; a crank arm, a first end of the crank arm being coupled to the drive shaft, and a second end of the crank arm opposite to the first end being coupled to the edge device; and a gear system (e.g. a strain wave gear system) coupled between the drive shaft and the first end of the crank arm.

FIELD OF THE INVENTION

The present invention relates to aircraft wing systems.

BACKGROUND

The wings of many different types of aircraft are equipped with highlift devices that are operable to increase the lift experienced by anaircraft wing. Such high lift devices may allow the wing to operate at ahigher angle of attack.

An example of a high lift device is a slat. In use, a slat may be movedaway from the leading edge of the fixed wing of an aircraft, therebycreating a gap between the slat and the wing under slat surface.Deploying slats in this way tends to allow an aircraft to fly at slowerspeeds, or take off and land in shorter distances.

A different, separate example of a high lift device is a leading edgeflap, or a droop. Droops are leading edge sections that rotate downwardsrelative to a fixed aircraft wing. In contrast to a slat, the droop doesnot move away from the wing leading edge when it is deployed, and thusno gap between the droop and the wing under flap surface is created.

U.S. Pat. No. 4,399,970 discloses a wing leading edge slat actuation andpositioning system. The system having a number of positions:—a stowed orretracted position; a first operative position where the upper surfaceof the slat and the upper surface of the fixed wing section form asubstantially smooth and continuous upper surface; and a furtherextended position where a slot is formed between the leading edge of thefixed wing portion and the trailing edge of the extended slat panel.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides an aircraft wingsystem comprising: an aircraft wing; an edge device coupled to a leadingedge or trailing edge of the aircraft wing; a drive shaft rotatableabout its axis; a crank arm, a first end of the crank arm being coupledto the drive shaft, and a second end of the crank arm opposite to thefirst end being coupled to the edge device; a gear device coupledbetween the drive shaft and the first end of the crank arm; a furthercrank arm, a first end of the further crank arm being coupled to thedrive shaft, and a second end of the further crank arm opposite to thefirst end being coupled to the edge device, the further crank arm beingspaced apart from the crank arm along a length of the drive shaft; and afurther gear system coupled between the drive shaft and the first end ofthe further crank arm; wherein a length of the crank arm may bedifferent to that of the further crank arm.

The crank arm may be arranged to convert circular motion of the driveshaft to a reciprocating motion of the edge device.

The gear device may be configured such that a relatively higher speedrotation of the drive shaft causes a relatively lower speed rotation ofthe first end of the crank arm.

The gear device may be a strain wave gear device, for example, aHarmonic Drive gear device.

A gear ratio of the gear device may be equal to that of the further geardevice.

The drive shaft may extend at least partially along a length of theaircraft wing. The crank arm may be shorter than the further crank arm.The crank arm may be located closer to a tip of the aircraft wing thanthe further crank arm.

The edge device may comprise a fairing coupled to the leading edge ofthe aircraft wing. The actuation means may be configured to move thefairing relative to the aircraft wing between a stowed position, a firstdeployed position, and a second deployed position. The stowed positionmay be when the fairing is in contact with the aircraft wing and thefairing serves as a continuation of the aircraft wing. The firstdeployed position may be when the fairing is in contact with theaircraft wing and located below the stowed position. The second deployedposition may be when the fairing is spaced apart from the leading edgeof the aircraft wing, thereby defining a gap between the fairing and theleading edge through which air may flow.

The actuation means may be configured to move the fairing relative tothe aircraft wing between the stowed position and the first deployedposition by rotating the fairing about a first axis. The actuation meansmay be configured to move the fairing relative to the aircraft wingbetween the first deployed position and the second deployed by rotatingthe fairing about a second axis. The second axis may be different to thefirst axis (e.g. the first and second axes may be spaced apart).

Rotating the fairing about the first axis may cause a portion of thefairing to slide over a surface of the aircraft wing while remaining incontact with the surface of the aircraft wing.

The aircraft wing system may further comprise a guiding system forguiding movement of the edge device relative to the aircraft wing. Theguiding system may comprise: a bracket fixed to either the edge deviceor the aircraft wing, the bracket comprising two roller tracks; and tworollers fixed to the other of the one of the edge device and theaircraft wing than the one to which the bracket is fixed, the rollersbeing fitted in respective roller tracks of the bracket, each rollerbeing configured to roll along the roller track to which it is fitted.

At least one roller track may comprise a first curved portion and asecond curved portion joined together to form a continuous track. Thefirst curved portion may have a different curvature to the second curvedportion.

In a further aspect, the present invention provides an aircraftcomprising an aircraft wing system according to any of the precedingaspects.

In a further aspect, the present invention provides an aircraft wingsystem comprising: an aircraft wing; an edge device coupled to a leadingedge or trailing edge of the aircraft wing; a drive shaft rotatableabout its axis; a crank arm, a first end of the crank arm being coupledto the drive shaft, and a second end of the crank arm opposite to thefirst end being coupled to the edge device; a gear device coupledbetween the drive shaft and the first end of the crank arm; and aguiding system for guiding movement of the edge device relative to theaircraft wing. The guiding system may comprise: a bracket fixed toeither the edge device or the aircraft wing, the bracket comprising tworoller tracks; and two rollers fixed to the other of the one of the edgedevice and the aircraft wing than the one to which the bracket is fixed,the rollers being fitted in respective roller tracks of the bracket,each roller being configured to roll along the roller track to which itis fitted.

In a further aspect, the present invention provides a method ofoperating an aircraft wing system. The aircraft wing system comprises:an aircraft wing; an edge device coupled to a leading edge or trailingedge of the aircraft wing; a drive shaft rotatable about its axis; acrank arm, a first end of the crank arm being coupled to the driveshaft, and a second end of the crank arm opposite to the first end beingcoupled to the edge device; and a gear system coupled between the driveshaft and the first end of the crank arm. The method comprises rotatingthe drive shaft so as to cause circular motion of the first end of thecrank arm, thereby moving, relative to the aircraft wing, the edgedevice coupled to the second end of the crank arm.

In a further aspect, the present invention provides a method ofproducing an aircraft wing system, the method comprising: providing anaircraft wing; and coupling an edge device to a leading edge or trailingedge of the aircraft wing by: providing a drive shaft rotatable aboutits axis; coupling a first end of a crank arm to the drive shaft;coupling a second end of the crank arm opposite to the first end to theedge device; and coupling a gear device between the drive shaft and thefirst end of the crank arm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration (not to scale) of an aircraft;

FIG. 2 is a schematic illustration (not to scale) showing a side viewcross section through an aircraft wing and an associated leading edgesystem;

FIGS. 3 to 5 are schematic (not to scale) sectional views of the leadingedge of the aircraft wing and respectively show a fairing of the leadingedge system in retracted, dropped, and extended positions;

FIG. 6 is a schematic illustration (not to scale) of showing the fairingfrom its trailing edge side;

FIG. 7 is a schematic illustration (not to scale) is a cross sectionthrough the leading edge of the aircraft wing and fairing;

FIG. 8 is a schematic illustration (not to scale) showing an aircraftwing substructure, and the drive system for moving the fairing; and

FIG. 9 is a schematic illustration (not to scale) showing the fairingfrom its trailing edge side, and a portion of the drive system coupledthereto.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration (not to scale) of an aircraft 100comprising two wings 102. Each aircraft wing 102 comprises an embodimentof a leading edge system 104 located at the leading edge of that of thataircraft wing 102.

FIG. 2 is a schematic illustration (not to scale) showing a side viewcross section through an aircraft wing 102 and the leading edge system104 located thereon.

In this embodiment, the leading edge system 104 comprises a profiledfairing 200 and a coupling mechanism 202. The fairing 200 is attached tothe leading edge of the aircraft wing 102 via the coupling mechanism202.

In some embodiments, the fairing 200 includes a stiffening structure,for example one or more longitudinal stiffeners, which may be attachedto a rear/trailing edge side of the fairing 200.

The coupling mechanism 202 is operable to move the fairing 200 withrespect to the aircraft wing 102. Positions with respect to the aircraftwing 102 to which the fairing 200 may be moved are described in moredetail later below with reference to FIGS. 3 to 5.

The coupling mechanism 202 and the operation thereof is described inmore detail later below with reference to FIGS. 6 to 8.

FIG. 3 is a schematic illustration (not to scale) showing the aircraftwing 102 and also showing the fairing 200 in a “retracted position” (orstowed).

In this embodiment, in the retracted position, the leading edge of thewing 102 is embraced by the profiled fairing 200. The shape of thefairing 200 matches the profile of the wing 102 such that, in theretracted position, the fairing 200 contacts the wing 102 at the upperand lower surfaces of the wing leading edge.

In this embodiment, in the retracted position, the upper surface of thefairing 200 is substantially contiguous with the upper surface of theaircraft wing 102. Thus, where the fairing 200 contacts the uppersurface of the aircraft wing 102, the upper surface of the fairing 200and the upper surface of the aircraft wing 102 lie in a common planesaid common plane being indicated in FIG. 3 by a dotted line and thereference numeral 300.

In the retracted position, the lower surface of the fairing 200 may besubstantially contiguous with the lower surface of the aircraft wing102. In the retracted position, the lower surface of the fairing 200 maybe in contact with the lower surface of the aircraft wing 102.

In an example use, the fairing 200 is positioned in the retractedposition shown in FIG. 3 while that aircraft 100 is cruising atrelatively high speed.

The coupling mechanism 202 may be operated to move the fairing 200relative to the aircraft wing 102 from the retracted position to a“dropped position” and vice versa.

FIG. 4 is a schematic illustration (not to scale) showing the aircraftwing 102, and also showing the fairing 200 in the dropped position.

To move the fairing 200 from the retracted position to the droppedposition, the fairing 200 is rotated downwards relative to the aircraftwing 102 about a first axis (not shown in the Figures). In thisembodiment, this rotation is performed such that the upper portion ofthe fairing 200 slides over the upper portion of the leading edge of thewing 102. Throughout this rotation, the upper portion of the fairing 200remains in contact with the upper surface of the aircraft wing 102.

Thus, in this embodiment, in the dropped position, the upper portion ofthe fairing 200 remains in contact with the upper surface of theaircraft wing 102 such that there is no gap between the fairing 200 andthe wing 102 at the upper surface of the leading edge of the wing 102.

To move the fairing 200 into the dropped position, the fairing 200 isrotated downwards with respect to the aircraft wing 102 such that theupper surface of the fairing 200 is at a first angle 400 with the plane300. In this embodiment, the first angle is 8°. Thus, moving the fairing200 from the retracted position to the dropped position includesrotating the fairing 200 downwards (i.e. in a direction from the upperwing surface towards the lower wing surface) with respect to the wing102, by 8°, i.e. from 0° to 8° from the plane 300. In other embodiments,the first angle has a different value, i.e. other than 8°.

In this embodiment, in the dropped position, the upper surface of thefairing 200 is substantially contiguous with the upper surface of theaircraft wing 102. In this embodiment, the upper surface of the fairing200 remains substantially contiguous with the upper surface of theaircraft wing 102 throughout its rotation through the first angle.

In this embodiment, in the dropped position, the lower surface of thefairing 200 is not in contact with the lower surface of the aircraftwing 102, i.e. there is a gap (hereinafter referred to as the “firstgap” 402) between the lower surface of the fairing 200 and the lowersurface of the aircraft wing 102.

In the dropped position, the fairing 200 acts to increase the lift onthe aircraft wing 102 compared to when the fairing 200 is in theretracted position. By moving the fairing 200 from its retractedposition to its dropped position, in effect, the size of the suctionsurface of the aircraft wing 102 tends to be increased. Also, air flowover the aircraft wing 102 tends to remain attached to the upper surfaceof the wing 102 for an increased time. Thus, lift tends to be increased.

Furthermore, moving the fairing 200 from its retracted position to itsdropped position tends to alter the camber of the aircraft wing 102 andreduce its stalling speed. Thus, stall characteristics of the aircraftwing 102 tend to be changed. This tends to allow for a correction ofundesirable stall characteristics, for example, stall characteristicsthat cannot be corrected using a leading-edge slat because, whendeployed, gaps between a leading-edge slat and the aircraft wing arecreated.

In its dropped position, the fairing 200, in effect, tends to functionin a similar way to a droop.

In an example use, the fairing 200 is positioned in the dropped positionshown in FIG. 4 while that aircraft 100 is operating at relatively highspeed, and when increased lift, and/or an increase in theangle-of-attack at which the wing 102 will stall, is required.

The coupling mechanism 202 may be operated to move the fairing 200relative to the aircraft wing 102 from the dropped position to an“extended position” and vice versa.

FIG. 5 is a schematic illustration (not to scale) showing the aircraftwing 102 and also showing the fairing in an extended position.

To move the fairing 200 from the dropped position to the extendedposition, the fairing 200 is rotated downwards relative to the aircraftwing 102 about a second axis (bot shown in the Figures). In thisembodiment, the second axis is different to the first axis. Thisrotation is performed such that the fairing 200 is moved away from theleading edge of the wing 102, thereby creating a gap (hereinafterreferred to as the “second gap” 500) between the upper portion of thefairing 200 and the upper surface of the leading edge of wing 102. Also,this rotation tends to increase the size of the first gap 402.

Thus, in this embodiment, in the extended position, the fairing 200 andthe leading edge of the aircraft wing 102 are spaced apart such that airmay flow between the fairing 200 and the aircraft wing 102, as indicatedin FIG. 5 by a dotted arrow and the reference numeral 502.

To move the fairing 200 into the extended position, the fairing 200 isfurther rotated downwards with respect to the aircraft wing 102 suchthat the upper surface of the fairing 200 is at a second angle 504 withthe plane 300. In this embodiment, the second angle is 17°. Thus, movingthe fairing 200 from the dropped position to the extended positionincludes rotating the fairing 200 downwards (i.e. in a direction fromthe upper wing surface towards the lower wing surface) with respect tothe wing 102, by 9°, i.e. from 8° to 17° from the plane 300. In someembodiments, the second angle has a different value, i.e. other than17°.

In the extended position, that the gap 402, 500 between the fairing 200and the wing 102, 500 tends to allow the wing 102 to work efficiently athigher angles of attack compared to, for example, when the fairing 200is in the retracted position. Also, when the fairing 200 is in theextended position, the aircraft wing 102 and fairing 200 system tend tohave relatively benign stall characteristics. Thus, by deploying thefairing 200 to its extended position, the aircraft 100 tends to becapable of flying at relatively slower speeds, or taking off and landingin shorter distances.

Moving the fairing 200 to its extended position tends to allow the wing102 to operate at a higher angle of attack compared to when the fairing200 was in its retracted or dropped position.

The fairing 200 may be deployed to its extended position when theaircraft 100 is landing or performing other manoeuvres which may takethe aircraft 100 close to the stall. The fairing 200 may be retractedfrom its extended position to either its dropped position or retractedposition when the aircraft 100 is operating at relatively higher speeds,for example, so as to reduce drag.

FIG. 6 is a schematic illustration (not to scale) of showing a thefairing 200 from its trailing edge side and showing a portion of thecoupling mechanism 202 that is fixedly attached to the fairing 200.Further details of the portion of the coupling mechanism located in theaircraft wing 102 are provided later below with reference to FIG. 7.

In this embodiment, the portion of the coupling mechanism 202 that isfixedly attached to the fairing 200 comprises two brackets 600 attachedto the fairing 200 at a certain distance from one another. The brackets600 are made of metal, such as titanium or steel.

FIG. 7 is a schematic illustration (not to scale) is a cross sectionthrough the leading edge of the aircraft wing 102 and fairing 200 takenthrough a bracket 600.

The bracket 600 comprises an arcuate portion 700 terminating at thefairing end in a plate 702 attached to a supporting member 704 fixed tothe fairing 200, and guided at its other end in the leading edge sectionof the wing 102.

Each bracket 600 comprises two roller tracks or slots, namely a firstroller track 706 and a second roller track 708. In this embodiment,guidance is achieved by rollers, including a first roller 710 and asecond roller 712 fitted into the first and second roller tracks 706,708 respectively. The rollers 710, 712 have spindles in the horizontalplane. The rollers 710, 712 are carried by a structure 714 arranged inthe wing 102, said structure 714 containing an opening 716 through whichthe bracket 600 moves in operation. For example, in some embodiments,the roller 710, 712 may be attached to respective ribs of the aircraftwing 102, said ribs being attached onto a front surface of a front sparof the aircraft wing 102.

In this embodiment, each first roller track 706 comprises two curvedportions, namely a first curved portion 718 and a second curved portion720. The first curved portion 718 extends from a proximal end of thefirst roller track 706 nearest the fairing 200, away from the fairing200 to the second curved portion 720. The second curved portion 720extends from the first curved portion 718 to a distal end of the firstroller track 706 furthest from the fairing 200. The first and secondcurved portions 718, 720 are connected to one another so as to provide acontinuous curved path along which the first roller 710 may roll.

In this embodiment, moving the fairing 200 from the retracted positionto the dropped position comprises the first roller 710 rolling along thefirst curved portion 718 of the first roller track 706, from theproximal end of the first track 706 to where the first curved portion718 joins the second curved portion 720. The first curved portion 718has a first radius of curvature such that the first roller 710 rollingalong the first curved portion 718 causes the fairing 200 to be rotateddownwards about the above mentioned first axis. Moving the fairing 200from the dropped position to the retracted position comprises the firstroller 710 rolling along the first curved portion 718 in the reversedirection.

In this embodiment, moving the fairing 200 from the dropped position tothe extended position comprises a the first roller 710 rolling along thesecond curved portion 720 of the first roller track 706, from where thesecond curved portion 720 joins the first curved portion 718 to thedistal end of the first track 706 furthest from the fairing 200. Thesecond curved portion 720 has a second radius of curvature such that thefirst roller 710 rolling along the second curved portion 720 causes thefairing 200 to be rotated downwards about the above mentioned secondaxis. In this embodiment, the second axis is different to the firstaxis. In this embodiment, the second radius of curvature is different tothe first radius of curvature. Moving the fairing 200 from the extendedposition to the dropped position comprises the first roller 710 rollingalong the second curved portion 720 in the reverse direction.

In this embodiment, each second roller track 708 comprises two curvedportions, namely a third curved portion 722 and a fourth curved portion724. The third curved portion 722 extends from a proximal end of thesecond roller track 708 nearest the fairing 200, away from the fairing200 to the fourth curved portion 724. The fourth curved portion 724extends from the third curved portion 722 to a distal end of the secondroller track 708 furthest from the fairing 200. The third and fourthcurved portions 722, 724 are connected to one another so as to provide acontinuous curved path along which the second roller 712 may roll.

In this embodiment, moving the fairing 200 from the retracted positionto the dropped position comprises the second roller 712 rolling alongthe third curved portion 722 of the second roller track 708, from theproximal end of the second track 708 to where the third curved portion722 joins the fourth curved portion 724. The third curved portion 722has a third radius of curvature such that the second roller 712 rollingalong the third curved portion 722 causes the fairing 200 to be rotateddownwards about the above mentioned first axis. Moving the fairing 200from the dropped position to the retracted position comprises the secondroller 712 rolling along the third curved portion 722 in the reversedirection.

In this embodiment, moving the fairing 200 from the dropped position tothe extended position comprises a the second roller 712 rolling alongthe fourth curved portion 724 of the second roller track 708, from wherethe fourth curved portion 724 joins the third curved portion 722 to thedistal end of the second track 708 furthest from the fairing 200. Thefourth curved portion 724 has a fourth radius of curvature such that thesecond roller 712 rolling along the fourth curved portion 724 causes thefairing 200 to be rotated downwards about the above mentioned secondaxis. In this embodiment, the fourth radius of curvature is different tothe third radius of curvature. Moving the fairing 200 from the extendedposition to the dropped position comprises the second roller 712 rollingalong the fourth curved portion 724 in the reverse direction.

The brackets 600 each having two tracks 706, 708 advantageously tends toprovide stability to the fairing 200 in use.

In this embodiment, the displacement of the fairing 200 with respect tothe wing 102 is produced by a drive system, as will now be described.

FIG. 8 is a schematic illustration (not to scale) showing substructure800 of an aircraft wing 102, and the drive system for moving the fairing200 with respect to the wing 102.

FIG. 9 is a schematic illustration (not to scale) showing the fairing200 from its trailing edge side, and a portion of the drive systemcoupled thereto.

In this embodiment, the drive system comprises a motor drive unit 802, adrive shaft 804, a plurality of strain wave gear devices 806, aplurality of cranks 808, and a plurality of connecting rods 810.

The motor drive unit 802 is fixedly attached to the wing substructure800. The motor drive unit 802 is configured to drive the drive shaft 804(i.e. to rotate the drive shaft 804 about its axis) under control of acontrol system (not shown). The motor drive unit 802 may be, forexample, an electric or hydraulic motor.

In this embodiment, the drive shaft 804 comprises a plurality of driveshaft sections coupled together by flexible couplings. Thisadvantageously tends to allow for wing flexion. Nevertheless, in someembodiments, the drive shaft 804 may be a continuous, single shaft.

In this embodiment, the strain wave gear devices 806 are spaced apartalong the length of the drive shaft 804. The strain wave gear devices806 are attached to respective shaft sections of the drive shaft 804. Inthis embodiment, the strain wave gear devices 806 are Harmonic Drive(Trademark) gearboxes. The strain wave gear devices 806 all have thesame gearbox ratio. In this embodiment, each strain wave gear device 806couples a respective crank 808 to the drive shaft 804. In someembodiments, gear systems other than Harmonic Drive (Trademark)gearboxes may be used.

Each crank 808 is an arm that is attached at one end at right angles tothe drive shaft 804 via a respective strain wave gear devices 806. Theother end of each crank 808 (i.e. the end opposite the end that iscoupled to the drive shaft 804) is attached to a respective connectingrod 810 by a pivot.

Each connecting rod 810 is connected at one end to a respective crank808 by a pivot, and at its opposite end to the fairing 200. In someembodiments, the connecting rods 810 have different lengths dependentupon their positions along the length of the aircraft wing 102. Forexample, connecting rods 810 closer to the wing tip may be shorter thanthose closer the aircraft fuselage.

In this embodiment, the strain wave gear devices 806 convert highvelocity rotational movement of the drive shaft 804 into a high force,small distance movement of the cranks 808. The cranks 808 and connectingrods 810 are used to convert the circular motion imparted to them by thedrive shaft 804 via the strain wave gear devices 806 into areciprocating motion of the fairing 200. The end of each connecting rods810 attached to a crank 808 moves in a circular motion, while the otherend that is attached to the fairing 200 moves in a curvilinear slidingmotion guided by the coupling mechanism 202 (i.e. by the brackets 600and rollers 710, 712). Thus, rotation of the drive shaft 804 by themotor drive unit 802 causes rotation of the fairing 200 with respect tothe aircraft wing 102.

Advantageously, the strain wave gear devices 806 may be thesubstantially the same as one another. In this embodiment, the strainwave gear devices 806 advantageously tend to harmonise the motion of thecranks 808 caused by rotation of the drive shaft 804. Therefore, for agiven position along the length of the aircraft wing 102, it tends to bepossible to achieve a desired movement range of the fairing 200 at thatposition by adjusting only the length of the crank 808 and/or theconnecting rod 810 at that position. This tends to be different toconventional systems in which, for different positions along the lengthof the aircraft wing 102, differently configured actuators (e.g. linearactuators) are used.

The strain wave gear devices 806 are advantageously simple, andlightweight.

Thus, embodiments of the leading edge system 104 are provided.

In the above embodiments, the fairing may be moved from its retractedposition to its dropped position and vice versa. Also, the fairing maybe moved from its dropped position to its extended position, and viceversa. However, in other embodiments, the leading edge system isconfigured such that the fairing is moved in a different way. Forexample, in some embodiments, the fairing may be from between itsretracted position and extended position, without being moved throughits dropped position.

In the above embodiments, the drive system is used to move the fairingas described in more detail above with reference to FIGS. 2 to 6.However in other embodiments, the drive system is used to drive adifferent leading edge device such as a leading edge slat, a droop, aKrueger flap, or a leading edge cuff.

The above described embodiments are given purely as examples and areopen to modification, in particular by the substitution of equivalenttechniques or systems, without in so doing departing from the scope ofthe invention.

What is claimed is: 1: An aircraft wing system comprising: an aircraftwing; an edge device coupled to a leading edge or trailing edge of theaircraft wing; a drive shaft rotatable about its axis; a crank arm, afirst end of the crank arm being coupled to the drive shaft, and asecond end of the crank arm opposite to the first end being coupled tothe edge device; a gear system coupled between the drive shaft and thefirst end of the crank arm; a further crank arm, a first end of thefurther crank arm being coupled to the drive shaft, and a second end ofthe further crank arm opposite to the first end being coupled to theedge device, the further crank arm being spaced apart from the crank armalong a length of the drive shaft; and a further gear system coupledbetween the drive shaft and the first end of the further crank arm;wherein a length of the crank arm is different to that of the furthercrank arm. 2: The aircraft wing system according to claim 1, wherein thecrank arm is arranged to convert circular motion of the drive shaft(804) to a reciprocating motion of the edge device. 3: The aircraft wingsystem according to claim 1, wherein the gear system is configured suchthat a relatively higher speed rotation of the drive shaft causes arelatively lower speed rotation of the first end of the crank arm. 4:The aircraft wing system according to claim 1, wherein the gear systemis a strain wave gear system. 5: The aircraft wing system according toclaim 4, wherein the gear system is a Harmonic Drive gear system. 6: Theaircraft wing system according to claim 1, wherein a gear ratio of thegear system is the same as that of the further gear system. 7: Theaircraft wing system according to claim 1, wherein the drive shaftextends at least partially along a length of the aircraft wing; thecrank arm is shorter than the further crank arm; and the crank arm islocated closer to a tip of the aircraft wing than the further crank arm.8: The aircraft wing system according to claim 1, wherein: the edgedevice comprises a fairing coupled to the leading edge of the aircraftwing; the drive shaft, the crank arm, and the gear system are operableto move the fairing relative to the aircraft wing between a stowedposition, a first deployed position, and a second deployed position; thestowed position is when the fairing is in contact with the aircraft wingand the fairing serves as a continuation of the aircraft wing; the firstdeployed position is when the fairing is in contact with the aircraftwing and located below the stowed position; and the second deployedposition is when the fairing is spaced apart from the leading edge ofthe aircraft wing, thereby defining a gap between the fairing and theleading edge through which air may flow. 9: The aircraft wing systemaccording to claim 8, wherein the drive shaft, the crank arm, and thegear system are operable to move the fairing relative to the aircraftwing between the stowed position and the first deployed position byrotating the fairing about a first axis; the drive shaft, the crank arm,and the gear system are operable to move the fairing relative to theaircraft wing between the first deployed position and the seconddeployed by rotating the fairing about a second axis; and the secondaxis is a different axis to the first axis. 10: The aircraft wing systemaccording to claim 1, further comprising: a guiding system for guidingmovement of the edge device relative to the aircraft wing, the guidingsystem comprising: a bracket fixed to either the edge device or theaircraft wing, the bracket comprising two roller tracks; and two rollersfixed to the other of the one of the edge device and the aircraft wingthan the one to which the bracket is fixed, the rollers being fitted inrespective roller tracks of the bracket, each roller being configured toroll along the roller track to which it is fitted. 11: The aircraft wingsystem according to claim 10, wherein at least one roller trackcomprises a first curved portion and a second curved portion joinedtogether to form a continuous track, the first curved portion having adifferent curvature to the second curved portion. 12: An aircraftcomprising an aircraft wing system according to claim
 1. 13: A method ofoperating an aircraft wing system, the aircraft wing system comprising:an aircraft wing; an edge device coupled to a leading edge or trailingedge of the aircraft wing; a drive shaft rotatable about its axis; acrank arm, a first end of the crank arm being coupled to the driveshaft, and a second end of the crank arm opposite to the first end beingcoupled to the edge device; and a gear system coupled between the driveshaft and the first end of the crank arm; a further crank arm, a firstend of the further crank arm being coupled to the drive shaft, and asecond end of the further crank arm opposite to the first end beingcoupled to the edge device, the further crank arm being spaced apartfrom the crank arm along a length of the drive shaft; and a further gearsystem coupled between the drive shaft and the first end of the furthercrank arm; wherein a length of the crank arm is different to that of thefurther crank arm; the method comprising: rotating the drive shaft so asto cause circular motion of the first end of each crank arm, therebymoving, relative to the aircraft wing, the edge device coupled to thesecond end of each crank arm.